Alkoxy vinyl phosphono dithioates as herbicides



United States Patent 3,481,731 ALKOXY VINYL PHOSPHONO DITHIOATES AS HERBICIDES Erik K. Regel, Mission, Kans., and Marion F. Botts,

Independence, Mo., assignors to Chemagro Corporation, Kansas City, Mo., a corporation of New York No Drawing. Filed Jan. 27, 1967, Ser. No. 612,101

The portion of the term of the patent subsequent to Dec. 17, 1985, has been disclaimed Int. Cl. A01n 9/36 US. Cl. 7187 8 Claims ABSTRACT OF THE DISCLOSURE Compounds of the formula RiOCH=CHP where R is lower alkyl and R and R are lower alkyl, phenyl, alkyl phenyl or chlorophenyl are prepared by (1) reacting alkyl vinyl ethers with phosphorus pentachloride, (2) converting the complex to alkoxy 2-chloroethyl phosphonyldichloride by treatment with sulfur dioxide with simultaneous dehydrohalogenation to alkoxyvinylphosphonyldichloride and (3) reacting with two moles of a mercaptan in the presence of a tertiary amine. The new compounds are useful as preand post-emergent herbicides. S,S diisopropyl 2 isobutoxyvinylphosphonodithioate Was the overall best herbicide tested.

The present invention is related to the invention in Regel et a1. application 596,412, filed Nov. 23, 1966, now Patent No. 3,416,912 wherein 2-alkylthiovinylphosphono dithioates were prepared and found to have herbicidal activity.

The present invention relates to substituted vinylphosphonodithioates.

It is an object of the invention to prepare novel substituted vinyl phosphonodithioates.

Another object is to develop novel herbicides.

An additional object is to prepare herbicides having selective pre-emergent herbicidal activity.

A further object is to prepare herbicides having selective post-mergent herbicidal activity.

Still further objects and the entire scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications Within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

It has now been found that these objects are obtained by preparing compounds having the formula:

and applying them as preand post-emergent herbicides.

In the formulae R is lower alkyl, eg of 1 to 8 carbon atoms, most preferably of 1 to 4 carbons, R and R are alkyl of 1 to 8 carbons, phenyl, lower alkyl phenyl or chlorophenyl, R and R can be the same or diiferent.

3,481,731 Patented Dec. 2, 1959 ice S,S-diethyl-2-methoxyvinylphosphonodithioate, S,S-diisipropyl-2-methoxyvinylphosphonodithioate, S,S-dimethyl-Z-ethoxyvinylphosphonodithioate, S,S-diethyl-2-ethoxyvinylphosphonodithioate, S,S-dipropyl-2-ethoxyvinylphosphonodithioate, S,S-diisopropyl-Z-ethoxyvinylphosphonodithioate, S,S-dibutyl-2-ethoxyvinylphosphonodithioate, S,S-diphenyl-2-ethoxyvinylphosphonodithioate, S,S-diethyl-2-isobutoxyvinylphosphonodithioate, S,S dibutyl-2-isobutoxyvinylphosphonodithioate, S,S-dimethyl-2-rnethoxyvinylphosphonodithioate, S,S-dimethyl-Z-propoxyvinylphosphonodithioate, S,S-dimethyl-Z-isopropoxyvinylphosphonodithioate, S,S-dimethyl-2-butoxyvinylphosphonodithioate, S,S-dimethyl-2-sec. butoxyvinylphosphonodithioate, S-methyl-S-propyl-2-isobutoxyvinylphosphonodithioates, S,S-diethyl-Z-isoamyloxyvinylphosphonodithioate, S,S-diethyl-Z-octoxyvinylphosphonodithioate, S,S-dipropyl-2-methoxyvinylphosphonodithioate, S,S-dibutyl-Z-methoxyvinylphosphonodithio-ate, S,S-di sec. butyl-2-methoxyvinylphosphonodithioate, S,S-diamyl-2-methoxyvinylphosphonodithioate, S,S-dioctyl-2-methoxyvinylphosphonodithioate, S,S-diphenyl-Z-methoxyvinylphosphonodithioate, S,S-di-p-totyl-2-methoxyvinylphosphonodithioate, S,S-di-o-tolyl-2-methoxyvinylphosphonodithioate, S,S-di-p-butylphenyl-2-methoxyvinylphosphonodithioate, S,S-di-p-chlorophenyl-2-methoxyvinylphosphonodithioate, S-ethyl-S-p-chlorophenyl-2-methoxyvinylphosphonodithioate, S-ethyl-S-propyl-2-ethoxyvinylphosphonodithioate, S-propyl-S-butyl-2-ethoxyvinylphosphonodithioate, S,S-diamyl-Z-ethoxyvinylphosphonodithioate, S,S-dihexyl-Z-ethoxyvinylphosphonodithioate, S,S-dicyclohexyl-2-ethoxyvinylphosphonodithioate, S,S-diheptyl-2-ethoxyvinylphosphonodithioate, S,S-diphenyl-2-ethoxyvinylphosphonodithioate, S,S-di-o-chlorophenyl-2-ethoxyvinylphosphonodithioate, S,S-diethyl-2-propoxyvinylphosphonodithioate, S,S-dipropyl-2-propoxyvinylphosphonodithioate, S,S-dibutyl-Z-propoxyviuylphosphonodithioate, S,S-dihexyl-2-propoxyvinylphosphonodithioate, S,S-diisooctyl-Z-propoxyvinylphosphonodithioate, S,S-dim-tolyl-2-propoxyvinylphosphonodithioate, S,S-dipropyl-2-isopropoxyvinylphosphonodithioate, S,S-disiopropyl-2-isopropoxyvinylphosphonodithioate, S,S-dibutyl-2-isopropoxyvinylphosphonodithioate, S,S-diethyl-2-butoxyvinylphosphonodithioate, S,S-dihexyl-Z-butoxyvinylphosphonodithioate, S,S-diamyl-2-isobutoxyvinylphosphonodithioate, S,S-di 2',4'-dichlor0phenyl) -2-isobutoxyvinylphosphonm dithioate.

The compounds of Formula I are readily prepared by reacting an alkyl vinyl ether with phosphorus pentachloride preferably dissolved in a solvent such as carbon tetrachloride to form the 2-alkoxy-2-chloroethylphosphonyldichloride. The complex is treated with two moles of sulfur dioxide. Dehydrohalogenation of the intermediate formed in this reaction occurs simultaneously or upon removal of the phosphorus oxychloridethionylchloride-solvent mixture to yield alkoxyinylphosphonyldichloride. The alkoxyvinylphosphonodithioates are formed by esterification of the alkoxyvinylphosphonyldichloride with a mercaptan in the presence of a tertiary amine, e.g. triethylamine, tripropylamine, N,N-

ll 4) 23/811 ZNEta ROCH=CHP ZEt NHC As alkyl vinyl ethers as starting materials there can be employed methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, sec. butyl vinyl ether, amyl vinyl ether, isoamyl vinyl ether, hexyl vinyl ether, octyl vinyl ether, isooctyl vinyl ether.

As mercaptans there can be used methyl mercaptan, ethyl mercaptan, propyl mercaptan, isopropyl mercaptan, butyl mercaptan, isobutyl mercaptan, hexyl mercaptan, cyclohexyl mercaptan, amyl mercaptan, heptyl mercaptan, octyl mercaptan, isooctyl mercaptan, 2-ethylhexyl mercaptan, thiophenol, p-methylthiophenol, 2- chlorothiophenol, 2,4-dichlorothiophenol, 4-butylthiophen01.

Unless otherwise indicated all parts and percentages are by weight.

EXAMPLE 1 29 grams (0.5 mole) of methyl vinyl ether was added to a stirring suspension of 208 grams (1 mole) of phosphorus pe'ntachloride in 8-10 volumes of carbon tetrachloride. The reaction mixture was cooled to 10-20 C. throughout the addition. After the addition was completed, the reaction mixture was allowed to warm to room temperature (25 C.) and was then stirred for 12- 14 hours.

Gaseous sulfur dioxide was then bubbled into the stirring suspension at a rapid rate. Cooling was maintained at 10-20 C. throughout the addition. Completion of the reaction was evidenced by disappearance of the solid phase and the formation of a clear solution. The 2-methoxyvinyl phosphonyl dichloride was obtained by direct distillation of the reaction mixture, B.P. 85 C.; n 1.4997; yield 85%.

EXAMPLE 2 144 grams (2 moles) of ethyl vinyl ether was added dropwise to a stirring suspension of 833 grams (4 moles) of phosphorus pentachloride in 8-10 volumes of carbon tetrachloride. The reaction mixture was cooled to 10-20 C. throughout the addition. After the addition was completed, the reaction mixture was allowed to warm to room temperature and then stirred for 12-14 hours.

Gaseous sulfur dioxide was then bubbled into the stirring suspension at a rapid rate. Cooling was maintained at l0-20 C. throughout the addition. Completion of the reaction was evidenced by the disappearance of the solid phase and the formation of a clear solution. The 2-ethoxyvinylphosphonyldichloride was obtained by direct distillation of the reaction mixture, B.P.27 142 C.; n;, 1.4950; yield 75%.

EXAMPLE 3 100 grams (1 mole) of isobutyl vinyl ether was added dropwise to a stirring suspension of 417 grams (2 moles) of phosphorus pentachloride in 8-10 volumes of carbon tetrachloride. The reaction mixture was cooled to 10-20 4 C. throughout the addition. After the addition was completed, the reaction mixture was allowed to warm to room temperature (25 C.) and then stirred for 12-14 hours.

Gaseous sulfur dioxide was then bubbled into the stirring suspension at a rapid rate. Cooling was maintained at 10-20 C. throughout the addition. Completion of the reaction was evidenced by the disappearance of the solid phase and the formation of a clear solution.

The 2-isobutoxyvinylphosphonyldichloride was obtained by direct distillation of the reaction mixture, B.P. 92 C.; r15 1.48 68; yield 72%.

EXAMPLE 4 17.5 grams (0.1 mole) of 2-(methoxy)vinyl phosphonyl dichloride was diluted with 10 volumes of dry benzene. 12.5 grams (0.2 mole) of ethyl mercaptan was then added. 20.2 grams (0.2 mole) of triethylamine was added to this stirring solution at such a dropwise rate to keep the exothermic reaction temperature at 30-35 C. After the addition was completed, the reaction mixture was allowed to stir until room temperature was reached (25 C.).

The reaction mixture was then washed with cold water. (If the water wash was acid, as occurred in some experiments, the benzene layer was extracted with 5% sodium bicarbonate solution. The benzene layer was then further washed until all washes were neutral.) The benzene layer was then dried over anhydrous sodium sulfate. The solvent was stripped in vacuo on a steam bath; and the resulting crude oil was distilled to obtain S,S-diethyl-2- methoxyvinylphosphonodithioate (Compound 7374) as the product. B.P. C.; n 1.5529; yie1d=67%.

EXAMPLE 5 13.5 grames (0.08 mole) of 2-(methoxy)vinyl phosphonyl dichloride was diluted with 10 volumes of dry benzene. 12.5 grams (0.16 mole) of isopropyl mercaptan was then added. 15.2 grams (0.15 mole) of triethylamines was added to this stirring solution at such a dropwise rate to keep the exothermic reaction temperature at 30- 35 C. After the addition was completed, the reaction mixture was allowed to stir until room temperature was reached (25 C.).

The reaction mixture was then washed with cold water. (If the water wash was acid, as occurred in some experiments, the benzene layer was extracted with 5% sodium bicarbonate solution. The benezene layer was then further washed until all washes were neutral.) The benzene layer was then dried over anhydrous sodium sulfate. The solvent was stripped in vacuo on a steam bath; and the resulting crude oil was distilled to obtain S,S-diisopropyl- 2-methoxyvinylphosphonodithioate (Compound 7375) as the product.

B.P. 117 C.; n;, 1.5340; yield=75% EXAMPLE 6 19 grams (0.1 mole) of 2-(ethoxy)vinyl phosphonyl dichloride was diluted with 10 volumes of dry benzene. 11.5 grams (0.24 mole) of methyl mercaptan was then added. 20.2 grams (0.2 mole) of triethylamine was added to this stirring solution at such a dropwise rate to keep the exothermic reaction temperature at 30-35 C. After the addition was completed, the reaction mixture was allowed to stir until room temperature was reached (25 C.).

The reaction mixture was then washed with cold water. The benzene layer was then dried over anhydrous sodium sulfate. The solvent was stripped in vacuo on a steam bath; and the resulting crude oil was distilled to obtain S,S dimethyl 2 ethoxyvinylphosphonodithioate (Compound 7579) as the product.

B.P. C.; 11 1.5456; yield=94% EXAMPLE 7 19 grams (0.1 mole) of 2-(ethoxy) vinyl phosphonyl dichloride was diluted with volumes of dry benzene. 12.5 grams (0.2 mole) of ethyl mercaptan was then added. 20.2 grams (0.2 mole) of triethylamine was added to this stirring solution at such a dropwise rate to keep the exothermic reaction temperature at 30-35" C. After the addition was completed, the reaction mixture was allowed to stir until room temperature was reached (25 C.).

The reaction mixture was then washed with cold water. The benzene layer was then dried over anhydrous sodium sulfate. The solvent was stripped in vacuo on a steam bath; and the resulting crude oil was distilled to obtain S,S diethyl 2 ethoxyvinylphosphonodithioate (Compound 7576) as the product.

B.P. 126 C.; n 1.5456; yield=94% EXAMPLE 8 19 grams (0.1 mole) of Z-(ethoxy) vinyl phosphonyl dichloride was diluted with 10 volumes of dry benzene. 16 grams (0.22 mole) of l-propanethiol was then added. 20.2 grams (0.2 mole) of triethylamine was added to this stirring solution at such a dropwise rate to keep the exothermic reaction temperature at 30-35 C. After the addition was completed, the reaction mixture was allowed to stir until room temperature was reached (25 C.).

The reaction mixture was then washed with cold water. The benzene layer was then dried over anhydrous sodium sulfate. The solvent was stripped in vacuo on a steam bath; and the resulting crude oil was distilled to obtain S,S dipropyl 2 ethoxyvinylphosphonodithioate (Compound 7577) as the product.

19 grams (0.1 mole) of 2-(ethoxy)vii. phosphonyl dichloride was diluted with 10 volumes or dry benzene. 16.7 grams (0.22 mole) of 2-propanethiol was then added. 20.2 grams (0.2 mole) of triethylamine was added to this stirring solution at such a dropwise rate to keep the exothermic reaction temperature at 30-35 C. After the addition was completed, the reaction mixture was allowed to stir until room temperature was reached (25 C.).

The reaction mixture was then washed with cold water. The benzene layer was then dried over anhydrous sodium sulfate. The solvent was stripped in vacuo on a steam bath; and the resulting crude oil was distilled to obtain S,S,-diisopropyl-Z-ethoxyvinylphosphonodithioate (Compound 7578) as the product.

B.P. 115 C.; 11 1.5269; yield=75% EXAMPLE 10 19 grams (0.1 mole) of 2-(ethoxy)vinyl phosphonyl dichloride was diluted with 10 volumes of dry benzene. 18.5 grams (0.2 mole) of l-butanethiol was then added. 20.2 grams (0.2 mole) of triethylamine was added to this stirring solution at such a dropwise rate to keep the exothermic reaction temperature at 3035 C. After the addition was completed, the reaction mixture was allowed to stir until room temperature was reached C.).

The reaction mixture was then washed with cold water. The benzene layer was then dried over anhydrous sodium sulfate. The solvent was stripped in vacuo on a steam bath; and the resulting crude oil was distilled to obtain S,S dibutyl 2 ethoxyvinyl phosphonodithioate (Compound 7580) as the product. B.P. 147 C.; n 1.5251; yield=92%.

EXAMPLE 11 19 grams (0.1 mole) of 2-(ethoxy)vinyl phosphonyl dichloride was diluted with 10 volumes of dry benzene.

24 grams (0.22 mole) of thiophenol was then added. 20.2 grams (0.2 mole) of triethylamine was added to this stirring solution at such a dropwise rate to keep the exothermic reaction temperature at 3035 C. After the addition was completed, the reaction mixture was allowed to stir until room temperature was reached 25 C.).

The reaction mixture was then Washed with cold water, The benzene layer was then dried over anhydrous sodium sulfate. The solvent was stripped in vacuo on a steam bath; and the resulting crude oil was distilled to obtain S,S diphenyl 2 ethoxyvinylphosphonodithioate (Compound 7604) as the product. M.P. 82 C.; yield=98%.

EXAMPLE 12 21.7 grams (0.1 mole) of 2-(isobutoxy)vinyl phosphonyl dichloride was diluted with 10 volumes of dry benzene. 13.7 grams (0.22 mole) of ethyl mercaptan was then added. 20.2 grams (0.2 mole) of triethylamine was added to this stirring solution at such a dropwise rate to keep the exothermic reaction temperature at 30-35 C. After the addition was completed, the reaction mixture was allowed to stir until room temperature was reached (25 C.).

The reaction mixture was then washed with cold water. The benzene layer was then dried over anhydrous sodium sulfate. The solvent was stripped in vacuo on a steam bath; and the resulting crude oil was distilled to obtain- S,S-diethyl 2 isobutoxyvinylphosphonodithoate (Compound 7675) as the product. 11 1.5291; yield-=%.

EXAMPLE 13 21.7 grams (0.1 mole) of 2-(isobutoxy)vinyl phosphonyl dichloride was diluted with 10 volumes of dry benzene. 16 grams (0.22 mole) of 2-propanethiol was then added. 20.2 grams (0.2 mole) of triethylamine was added to this stirring solution at such a dropwise rate to keep the exothermic reaction temperature at 30-25 C. After the addition was completed, the reaction mixture was allowed to stir until room temperature was reached The reaction mixture was then washed with cold water. The benzene layer was then dried over anhydrous sodium sulfate. The solvent was stripped in vacuo on a steam bath; and the resulting crude oil was distilled to obtain S,S diisopro-pyl 2 isobutoxyvinylphosphonodithioate (Compound 7676) as the product. B.P. 145 C.; 11 1.5226; yield=91%.

EXAMPLE 14 10.9 grams (0.05 mole) of 2-(isobutoxy)vinyl phosphonyl dichloride was diluted with 10 volumes of dry benzene. 10 grams (0.11 mole) of l-butanethiol was then added. 10.1 grams (0.1 mole) of triethylamine was added to this stirring solution at such a dropwise rate to keep the exothermic reaction temperature at 30-35 C. After the addition was completed, the reaction mixture was allowed to stir until room temperature was reached (25 C.).

The reaction mixture was then washed with cold water. The benzene layer was then dried over anhydrous sodium sulfate. The solvent was stripped in vacuo on a steam bath; and the resulting crude oil was distilled to obtain S,S-dibutyl 2 isobutoxyvinylphosphonodithioate (Com- 7677) as the product. 11 1.5142; yield=93%.

The herbicides of the present invention can be used alone or they can be applied together with inert solids to form dusts, or can be dispersed in a suitable liquid dilute, e.g. organic solvents or water.

There can also be added surface active agents or wetting agents and/or inert solids in the liquid formulations. In such case, the active ingredients can be from 0.01 to 95% by weight of the entire composition.

As organic solvents there can be employed hydrocarbons, e.g. benzene, toluene, xylene, kerosene, diesel fuel, fuel oil and petroleum naphtha, ketones such as acetone,

methyl ethyl ketone and cyclohexanone, chlorinated hydrocarbons such as carbon tetrachloride, chloroform, trichloroethylene, and perchloroethylene, esters such as ethyl acetate, amyl acetate and butyl acetate, ethers, e.g. ethylene glycol monomethyl ether and diethylene glycol taurate. Turkey red oil, sodium dibutyl naphthalene sulfonate, sodium lignin sulfonate, polyethylene glycol stearate, sodium dodecylbenzene sulfonate, tertiary dodecyl polyethylene glycol thioether (Nonionic 218), long chain ethylene oxide-propylene oxide condensation products, e.g.

monomethyl ether, alcohols, e.g. methanol, ethanol, iso- Pluronic 61 (molecular weight 1000), polyethylene glycol propanol, amyl alcohol, ethylene glycol, propylene glycol, ester of tall oil acids, sodium octyl phenoxyethoxyethyl butyl carbitol acetate and glycerine. Mixtures of water sulfate, tris (polyoxyethylene) sorbitan monostearate and organic solvents, either as solutions or emulsions, can (Tween 60), and sodium dihexyl sulfosuccinate. b employed, The compounds of the present invention were tested as The novel herbicides can also be applied as aerosols. pre-emergent herbicides at the indicated dosages against e.g. by dispersing them in air by means of a compressed the indicated plants. In this test the surface of the soil gas such as dichlorodifluorornethane or trichlorofluoro- Was sprayed with an acetone solution of the test commethane and other Freons and Genetrons, for example. pound the same day as the seeds were planted. The flats The pesticides of the present invention can also be apwhich were planted were 14 inches long, 10 inches wide plied with adjuvants or carriers such as talc, pyrophyllite, n 3.5 inches deep. 3 grams of the test material was synthetic fine silica, attapulgus clay, kieselguhr, chalk, diluted to ml. with acetone. Each ml. of this solution diatomaceous earth, lime, calcium carbonate, bentonite, when applied to the flat was equivalent to 1 1b./ acre of Fullers earth, cottonseed hulls, wheat flour, soybean flour, test al (active ingredient)- Th6 requisite number pumice, tripoli, wood flour, walnut shell flour, redwood 20 of ml. of the acetone solution was diluted to ml. and flou and lignin, this diluted mixture was sprayed on the flats, e.g. for 15 As stated, it is frequently desirable to incorporate a lbs/acre 15 ml. of the original acetone solution was disurface active agent in the herbicidal compositions of the luted to 40 m With acetone d or 5 lbs./ acre 5 ml. of present invention. Such surface active or wetting agents the original acetone solution was diluted to 40 ml. with are advantageously employed in both the olid and liquid 25 acetone. In the pre-emergent herbicide test the results are compositions, The surface active agent can be anionic, expressed on a 0-10 scale With 0 indicating no effect and cationic or nonionic in character. 10 indicating complete inhibition of seeds to germinate Typical classes of surface active agents include alkyl and emerge The results ill thfi pfs-emel'gent herbicide sulfonate salts, alkylaryl sulfonate salts, alkylaryl polyare set forth in Table 1.

TABLE 1 Lbs. AI per Sugar Morning Wild Water Johnson acre Oats beets glory Radish Flax Millet Pigweed mustard grass grass Compound:

ether alcohols, fatty acid esters of polyhydric alcohols and the alkylene oxide addition products of such esters, and addition products of long chain mercaptans and alkylene oxides. Typical examples of such surface active agents include the sodium alkylbenzene sulfonates having 10 to 18 carbon atoms in the alkyl group, alkylphenol ethylene oxide condensation products, e.g. p-isooctylphenol condensed with 10 ethylene oxide units, soaps, e.g. sodium stearate and potassium oleate, sodium salt of propyl-naphthalene sulfonic acid, di (Z-ethylhexyl) ester of sodium sulfosuccinic acid, sodium lauryl sulfate, sodium decane sulfonate, sodium salt of the sulfonated monoglyceride of cocoanut fatty acids, sorbitan sesquioleate, lauryl trimethyl ammonium chloride, octadecyl trimethyl ammonium chloride, polyethylene glycol lauryl ether, polyethylene glycol esters of fatty acids and rosin acids, e.g. Ethofat 7 and 13, sodium N-methyl-N-oleyl 9 were dissolved in acetone in the same manner as in the pre-emergent herbicide tests. The flats, however, were sprayed 10 to 14 days after planting and the herbicidal activity was observed one week after the application of 10 where R R and R are all alkyl groups of l to 4 carbon atoms.

4. A process according to claim 3 wherein the compound is applied to the soil prior to the emergence of the test compound. The results are set forth in Table 2. 5 the plant.

TABLE 2 per Wild Sugar Morning Water- Johnson Compound acre Pigweed mustard beets glory grass Millet grass 7675 s 10 10 10 9 s 2 4 3 7 e t 7677 s 10 1o 9 9 7 2 1o 9 s s. 7

All of the compounds tested showed high post-emergent 5. A process according to claim 4 wherein the cornherbicidal activity at the 8 lb./acre rate. S,S-diisopropylpound is selected from the group consisting of Z-methoxyvinylphosphonodithioate (Compound 7375 S S diiso propyl-2-methoxyv1nylphosphonodithioate, S,S dnsopropyl 2 1sobutoxyvmylphosphonodithloate SS diethy1 z ethoxyvinylphosphonodithioate; (compcfurfd 7676) and f P? S,S-di-n-propyl-2-ethoxyvinylphosphonodithioate; phonodithloate (Compound 7677) possessed hlgh activity S,s diisopropyl z ethoxyvinylphosphonodithioate; and even at the 2 Ill/acre level- S,S-diisopropyl-Z-isobutoxyvinylphosphonodithioate.

The most fi coinPound for overall preand Post- 6. A process according to claim 3 wherein the comemergeni herincldail acuvlty was Compound 7676' pound is applied to the plants after the emergence of What is claimed 1s: the plants A Proms? of klllmg l?lants compr ismg applying to 7. A process according to claim 6 wherein the comthe i zza g f tg 23213 13 efiectlve amount of a pound is selected from the group consisting of c u avm omp g e S,S-di1sopropyl-2-methoxyvinylphosphonodlthioate;

0 SR S,S-diisopropyl-2-isobutoxyvinylphosphonodithiote; and H i 40 S,S-dibutyl-Z-isobutoxyvinylphosphonodithioate. R 00H=0HP i 8. A process accordlng to claim 3 wherein the compound is S,S diisopropyl 2 isobutoxyvinylphosphonodithioate. where R 1s lower alkyl and R and R are selected References Cited from the group consisting of alkyl of 1 to 8 carbon UNITED STATES PATENTS atoms, phenyl, lower alkyl phenyl and chlorophenyl.

2. A process according to claim 1 wherein the com- Sggggg: pound is S,S diisopropyl 2 methoxyvinylphosphonodithioate. 3,294,876 12/1966 Regel 260-972 3. A process of killing plants comprising applying LEWIS GOTTS Prima EX to the plant habitat a herbicidally effective amount of ry animer a compound according to claim 1 having the formula CATHERINE MILLS Asslstant Exammer 0 SE, US. Cl. X.R. fll/ 260950, 956 

